An energy-saving technique attracts attention in which a temperature rise due to penetration of heat radiant energy of sunlight through a window glass into a room is curbed to minimize electrical energy for cooling.
In general, a laminated film in which a high refractive layer and a low refractive layer are alternately laminated adjusting respective optical film thicknesses has the property of selectively reflecting light or a specific wavelength. The use of a laminated film which transmits a visible light and has a selective reflectivity in which a near-infrared ray is selectively reflected, as a heat ray shield film used for windows or members for vehicles, is thus being attempted.
A near-infrared reflective film in which layers having different refractive indices, are alternately laminated is conventionally produced by a variety of methods. A method in which a dry film-forming method, such as vapor deposition or sputtering is used (see Patent Document 1), a method in which a UV-curable resin is used (see Patent Document 2) and a method in which a polymer resin is melt-extruded to obtain multiple layers (see Patent Document 3) are disclosed.